We've had a number of people show concern around "clock cheaters" or instances when the clocks may appear to make sudden adjustments. Here we explain what’s actually going on (it’s not the users) and how ChessCube handles it.

ChessCube manages all times centrally on our server, but each Users client keeps and displays a local version of the games time that is checked against the central server with each move. The delay comes in when a browser has a delay (lag) in fetching moves from the server. Here's whats happening:

Your move is sent from your board to the Chesscube server and then on to your opponents board. He makes a move and it is sent back to the servers and on to your board. The issue comes in when there is a delay (lag) in communicating with the server, which is why we keep time centrally on our servers and adjust the Users’ boards from there. (This also prevents clock manipulation by users as the client doesn’t actually control the time.)

Here is a simple example to show it in action:

Even in this very simple example of 3 moves with only one user experiencing lag and only when they are submitting a move (not receiving), there is a noticeable adjustment. Note that the User B sees their time go down and the User A's go up. In cases of higher lag these adjustments may seem far more severe.

Any lag (or latency) less than 2 seconds is accommodated for. (details here) In this case the first 2 sec is adjusted for, but User B is penalised for the remaining 2 sec of lag. You can see a players lag by the indicator bar next to their time:

The reason we maintain clocks centrally is so that times CANNOT be tampered with. Most other sites don't have this central check in place which actually makes them far more susceptible to someone modifying their times as it's all controlled by their client.

Knowing that the site's clock displays are likely understating your nearness to game end, playing faster than appears to be needed should compensate when there's high lag involved (eg. short red lag bars for one or both opponents, and/or jerky clock counting down displays which can also indicate high lag).

If you don't realize that, then those with high lag have an Advantage, since their opponents will tend to overestimate the amount of remaining time they have.